Enhanced thermal, safety and anti-hygroscopicity performance of core–shell ammonium perchlorate with a double coating layer

Abstract

A new core–shell structure AP/Cu-DABT/Cu(Pa)₂ (10 wt% each) (AP = ammonium perchlorate, DABT = 3,3′-diamino-5,5′-bis(1H-1,2,4-triazole), Pa = palmitic acid) with two coating layers was synthesized through two self-assembly reactions to improve the thermal decomposition performance, safety performance and moisture absorption resistance of AP. The results show that the surface of AP particles is uniformly and densely covered by Cu-DABT and Cu(Pa)₂ coatings successively. Compared with pure AP, the HTD (high-temperature decomposition) peak temperature and activation energy of the AP/Cu-DABT/Cu(Pa)₂ (10 wt% each) composite material were reduced by 74.7 °C and 117.67 kJ mol⁻¹, respectively, and the heat release increased by 1421.02 J g⁻¹. In addition, the burning rate and maximum flame temperature of the propellant containing the AP/Cu-DABT/Cu(Pa)₂ (10 wt% each) composite were increased by 8.7 mm s⁻¹ and 815.8 °C, respectively, compared with the propellant containing pure AP. Moreover, compared with pure AP, the contact angle of the AP/Cu-DABT/Cu(Pa)₂ (10 wt% each) composite with water increased by 89.15°, and the water content decreased by 0.38 wt%. The impact sensitivity and friction sensitivity of the composite material were reduced by 16.9 cm and 96%, respectively. Analysis shows that the Cu-DABT coating plays a major role in improving the thermal properties of the composite material, the burning rate and flame temperature of the propellant, while the Cu(Pa)₂ coating plays a major role in improving the hygroscopic performance and safety performance of the composite material. The composite material has good thermal decomposition properties, anti-hygroscopic properties and safety properties, so the composite material is very promising as a potential additive for solid propellants.